The long-term goal of this research is to determine how bacterial cells establish intracellular polarity, direct specific processes to the poles, and control the activity of polar processes. Many bacteria target organelles and/or processes specifically to the cell poles. Particularly, it has been shown that many pathogens polarly localize virulence factors, indicating that polar localization has implications in disease. The basic mechanisms for polar localization are unknown. In this work, development of Caulobacter crescentus is used as a model system for polarity. Polar development in this organism has been correlated with the subcellular localization and proteolytic processing of the protein PodJ, and C. crescentus cells that are inhibited in development show no PodJ processing, indicating that the stability of PodJ is tied to polar developmental processes. Other proteins similar to PodJ have been found in other organisms, including pathogens that demonstrate cellular polarity. By understanding the role of PodJ in controlling polar processes, it may be possible to extrapolate this knowledge to other bacterial systems. The specific aims of this work are: 1. generate mutations in PodJ that lead to increased protein stability and determine the affect of increased stability of PodJ-mediated polar processes, and 2. determine the role of the putative PodJ peptidoglycan binding domain in maintaining PodJ stability. A combination of site-directed mutagenesis of sequences predicted to impact PodJ stability, and unbiased genetic screens using powerful assays to identify PodJ stability mutants will be utilized. Analysis of mutant phenotypes will involve cell biology techniques, biochemistry techniques, and bacterial physiology assays. Several plant and animal pathogens demonstrate cellular polarity and polar localization of virulence factors, yet the basic mechanisms of bacterial polarity are unknown. Understanding the underlying methods of establishing and controlling bacterial polarity will facilitate easier access to specific strategies employed by pathogens, and enhance new strategies to combat their virulence.